ASSESSMENT OF ARTIFICIAL SUBSTRATES FOR COLLECTION OF HATCHERY-REAREDSILVER-LIP PEARL OYSTER (PINCTADA-MAXIMA, JAMESON) SPAT

This paper reports on three experiments in which artificial substrates were assessed for the collection of hatchery-reared silver-lip (or go ld-lip) pearl oyster, Pinctada maxima (Jameson), spat. In the first ex periment, pediveliger larvae were settled onto collectors made from a variety of materials: curved PVC slats; polypropylene rope; a combinat ion of PVC slats and polypropylene rope; and monofilament nylon. After 37 days, the rope and the combined PVC slat and rope collectors had s ignificantly higher numbers of spat (P < 0.05) than either nylon or PV C slat collectors. In a second experiment, PVC slat collectors were pl aced in a larval settlement tank in either a horizontal or vertical or ientation. Significantly greater numbers of spat (P < 0.001) were obse rved on horizontally positioned PVC slat collectors than on collectors positioned vertically. Regardless of orientation, the concave surface of PVC slats had significantly higher (P < 0.001) numbers of spat tha n the convex surface. In the third experiment, collection of P. maxima spat was compared between PVC slats with or without an epifloral biof ilm. :Significantly more (P < 0.001) spat attached to PVC slats with a biofilm than clean PVC slats. These results indicate that the choice of collector material, the surface orientation of collectors and metho d of collector preparation can optimise the collection of hatchery-rea red P. maximum spat. (C) 1998 Elsevier Science B.V. All rights reserve d.